Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh hai » thanh hai, nhanh hai, hang hai
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
hai cua » thai cua, dai cua, hoi cua
duc van » duc va, duc tan, duc manh
hieu ve » hieu va
mai hoi » mai khoi, dai hoi, lai hoi
sach v » sach va, sach y, sach 2
ma hoi » xa hoi, ma hoa, me hoi
v nang » va nang, vu nang, van nang
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach v nang ((ma hoi) or (mai hoi)). ((hieu ve) OR (hieu van)) pham duc van hanh hai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang ((ma hoi) OR (mai hoi)). ((hieu ve) OR (hieu van)) pham duc van hanh hai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v nang ((ma hoi) or (mai hoi)). ((hieu ve) OR (hieu van)) pham duc van hanh hai cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach v nang ((ma hoi) or (mai hoi)). ((hieu ve) OR (hieu van)) pham duc van hanh hai cua te*.